The reforms of the welfare system under the 1945 Labour government are usually regarded as fundamental in creating the post-war welfare state. Yet, measured by their financial implications, and viewed in comparison with either pre-war Britain or other Western European countries in the same period, these reforms appear strikingly limited. Far from bringing a ‘New Jerusalem’, the 1940s reforms seem to have brought into being an austere, minimalist structure of welfare provision. The reasons for this are examined, especially the forces shaping the new social security system. It is argued that the combination of the Labour government's economic priorities, its acceptance of the Beveridge legacy and the Treasury pressure to limit the Exchequer's financial contribution to the new system, led to this austerity.